Late and confused

Alice
So my cycle has always been regular within a 32-34 day cycle. I was on the pill for 6 years before getting married last year. I went of the pill in January and immediately went back to a 34 day cycle without missing a beat. While hubby and I are not actively TTC we are happy if it happens 
This month I had 3 days of brown spotting ( very light) a week before my period was due and then nothing! 
I am currently 13 days late but have had 3 negative pregnancy tests. The first was taken at the doctors 2 days before expected period (she thought I'd had implantation bleeding) and then another 3 days late and the third at a week late. 
I've had one strange dizzy spell and the past week my boobs have been sore to touch but other than that fine. 
Just wondering how concerned I should be... I have an appointment with my doctor in 2 weeks when she gets back from the doctors but worrying in the meantime 
Has anyone had anything similar? What was the outcome?